Our atmosphere extends far above our familiar weather features and far above where our highest planes fly, with many unexpected twists and turns in the temperature and composition. The MSISatmos App for iPhone/iPad/iPod Touch can help you picture the Earth's atmosphere from the ground out to at least 1000 km. This is not day to day weather, but the App uses the latest MSIS and HWM model to summarize real data taken with space age instruments during the second half of the twentieth century and represents one of the most comprehensive descriptions available for the atmosphere above 100 km. Version 3.0 includes plots for trace chemically active species in the Stratosphere and Mesosphere from an unpublished model of UARS data.
Here one sets primary geophysical parameters that describe the atmospheric situation for which results are desired. Numerical results are tabulated for the specified condition and these are also used as the basis of the plots. The wind tabulation provides the magnitude and compass direction from which the wind is blowing with 0 being a northerly wind in meteorological terms and 90 being an easterly wind (from the east).
Local time (or Local Solar Time) is approximately your usual standard time but more precisely should be 12 noon when the sun is on your longitude meridian.
One can choose to enter altitudes in kilometers or miles and see temperature results in degrees Kelvin (or Absolute), Centigrade, or Fahrenheit. Number densities are in number per cubic centimeter. Pressure is in Atmospheres (surface average 1.). Wind is in m/s (meters per second) or MPH (miles per hour) if altitude in miles switch is chosen.
Large and small numbers here and in plots are in scientific notation, e.g. 1.00E+6 is one million and 1.00E-6 is 1 millionth.
The F10.7 (10.7 cm solar radio strength) and Ap parameters are used to represent (are a surrogat for) the effects of varying far UV radiation and magnetic storms respectively on the far upper atmosphere. These numbers can be obtained from the web site http://www.swpc.noaa.gov/ftpdir/weekly/RecentIndices.txt and many other sites for a particular day, month or year. F10.7 of 70 represents quiet (low sunspot number) solar conditions and 230 a high level of solar activity. An Ap of 0 represents exceptionally quiet magnetic conditions and Ap 100 a large magnet storm with lots of aurora. While Ap has a defined maximum of 400, events of this magnitude are rare and data scarce, so the model results may exhibit unrealistic features.
Advanced Options make it possible to display model results for selected time and spacial variations as used in the original model development such as time averages or the diurnal (24 hr) variation only.
Plot Setup View
Here one selects the x (horizontal) coordinate and y (vertical) coordinate for a simple line plot or contour Plot. The limits of the x coordinate can also be set. The line plot can have a second y coordinate axis. Touch the blue background to exit the coordinate picker or Done on the keyboard after changing coordinate limits.
A special y coordinate called “MSIS Composition %” provides % composition for all constituents which are greater than 1% or a selected constituent (via the second picker wheel) available from the MSIS model. A special coordinate called “MSIS Composite Num/cm3 ” provides number densities for all the standard constituents available from the MSIS model. A special coordinate called “UARS Volume Mixing Ratio” provides volume mixing ratios for All constituents from the UARS model or a selected constituent (via the second picker wheel) in units which may be parts per million (ppmv), billion (ppbv) or trillion (pptv).
The Vector Plot option adds wind vectors to the contour plots when possible.
Simply displays the selected plot or an error message if no plot is possible. The plots against altitude have the altitude axis automatically placed vertically. Some of these altitude plots indicate the approximate location of the primary atmospheric regions.
Contour plots indicate by color dots the temperature or other parameter as noted in the legend.
Wind vectors, when plotted, are viewed as pointing up on the screen for northward (blowing toward the north) and to the right for eastward wind at the particular x and y plot coordinates. Selecting a contour coordinate of None shows just the wind vectors. In the Legend, MaxW and MinW indicate the maximum and minimum wind speed in the chosen units (m/s or mph). These vectors show up better on an iPad.